Consistent attempts are made to improve medical imaging during interventions, wherein as few s as possible are simultaneously to be radiated onto the body of a patient. It is in many instances also very desirable to keep the stress on the body, such as on the kidneys, caused by the contrast agent which is required for x-ray recordings, to a minimum. One example to which this applies is the insertion of a new aortic valve. This example is subsequently used as an application area for the present application, without restricting the generality, wherein the application is naturally not restricted hereto.
Failure of the aortic valve, which is among the most frequent of valve faults, frequently results in damage and malfunction of the aortic valve. Contrary to the other valves within the heart, the aortic valve controls the flow of oxygen-rich blood, which is pumped out of the left ventricle into the aorta, which, as is generally known, is the main artery leading into the body.
The implantation of an aortic valve can be implemented as a minimally invasive heart operation, with which a faulty aortic valve is replaced by an artificial aortic valve. During the operation, real time fluoroscopy is frequently used by generating 2D x-ray images in order to provide navigation for the intervention. The problem nevertheless arises here of the aorta root barely being visible in the fluoroscopy images, if no contrast agent is injected. “Aorta root” is to be understood as the region of the aorta where it passes into and/or leaves the heart, in more precise terms, its left ventricle. Administration of (too much) contrast agent may however be problematic in many instances, because this may result for instance in renal insufficiency and injury to the patient. For this reason, it frequently occurs that a patient-specific aorta model, obtained by information extracted from an image, which is enriched with additional information, is merged with a fluoroscopy recording, i.e. superimposed and registered. In this way, a catheter can be localized in respect of the aortic valve and an optimal projection angulation for image representation can be determined for the subsequent implantation. The patient-specific aorta model is usually based on a segmentation of the aorta in preoperatively recorded CT volume data, of which a spatial recording by a C-arm device forms part.
If the patient-specific aorta model is overlaid with the fluoroscopy images, the physicians expect the model to move according to the heart and breathing movements of the patient, since an aorta model synchronized to the movement provides more accurate positioning information for the heart specialists during the replacement of the valve. A movement synchronization of this type is however currently only possible at the cost of a very high and thus possibly damaging contrast agent administration for the constant recording of a three-dimensional x-ray image.
DE 10 2008 030 244 A1 discloses a method for supporting percutaneous interventions, in which 2D x-ray recordings at different projection angles of an object range are recorded prior to the intervention using a C-arm x-ray system or a robot-based x-ray system and 3D image data of the object range is reconstructed from the 2D x-ray recordings. One or more 2D or 3D ultrasound images are recorded prior to and/or during the intervention using an external ultrasound system and are registered with the 3D image data. The 2D or 3D ultrasound images are then overlaid with the 3D image data record or a target area segmented therefrom or shown adjacent to one another in the same perspective.